Lecture 4 Flashcards
Evidence for extinction? (3•)
•Fossil organisms that are not living today
•Darwin’s interpretation that species change
•The # of species have changed through time.
Transitional forms?
Characteristics somewhat present between older and younger species.
Evidence for transitional forms?
•Organisms are related
•Organisms occurred at different times.
Pseudogenes?
Genes that are non-functional but have DNA sequences similar to that of functional genes.
Genetic Homology?
Similarity in DNA or amino acid sequences in different species.
Developmental Homologies?
Similarity in embryonic traits.
Structural Homologies?
When specific structures are similar in different species (but maybe with different organization.
What must happen for natural selection to occur?
•Traits must be heritable
•Genetic variation with a species for a trait
•The trait must increase fitness.
Tuberculosis (TB)?
A potential fatal lung infection that is caused by the bacteria, Mycobacterium.
Why can a mutation that can cause resistance to an antibiotic only occur if the antibiotic is present?
The mutation decreases fitness compared to others without the antibiotic but increases fitness compared to others with the antibiotic.
Why can’t you assume that a phenotypic variation has a genetic basis?
Because phenotypes can depend on environmental cause.
Adaptation?
Any heritable trait that increases the fitness of an individual.
What criteria must be met for a trait to be an adaptation?
•Heritable
•Functional
•Adaptive
Trait must increase the fitness of the organism
•Current function
the trait evolved the same time as the current function.
Natural selection only occurs when competition is present?
No
!Acclimation?
When there is environmental changes and individuals are able to respond to them temporarily. (E.g. avoidance)
Adaptation only occurs when?
A population changes in response to natural selection.
Acclimation occurs in an individuals?
Lifespan
Criteria for artificial selection?
•There must be genetic variation
•traits must have a genetic basis
•the trait is favoured by the gardener, not by differences in fitness
Criteria for sexual selection?
•when traits are sexually preferable (many mating strategies by birds)
Why is asymmetry in sex important for sexual selection?
When one sex has a trait that decreases fitness but increases fitness in another sex. The sex with the worse fitness can impress with the sex that has the better fitness.
Evolution by natural selection changes the?
Population, not individual.
What does it mean if a question concludes WITH CERTAINTY if an evolutionary mechanism is responsible?
It is always NO.
!What are the three main reasons that genetic drift can alter allele frequencies randomly? (3•)
•Mating opportunities
•Survival
•Game contribution to the next generation.
!When something is random, is it always truly random?
No (e.g. individuals may prefer to mate with an individual with a certain phenotype)
